Add @JsonIgnoreProperties(ignoreUnknown = true) to capability sub-records#852
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…ords The top-level ClientCapabilities and ServerCapabilities records have @JsonIgnoreProperties(ignoreUnknown = true) but their nested sub-records do not. Since ObjectMapper defaults to FAIL_ON_UNKNOWN_PROPERTIES = true, unknown fields on sub-objects cause deserialization failures. This already caused a real breakage when elicitation gained form/url fields (modelcontextprotocol#724). The MCP spec explicitly does not close capability objects (additionalProperties is never set to false), so SDKs must tolerate unknown fields for forward compatibility. Add the annotation to: - ClientCapabilities.Sampling - ClientCapabilities.Elicitation, Elicitation.Form, Elicitation.Url - ServerCapabilities.CompletionCapabilities - ServerCapabilities.LoggingCapabilities - ServerCapabilities.PromptCapabilities - ServerCapabilities.ResourceCapabilities - ServerCapabilities.ToolCapabilities Fixes modelcontextprotocol#766 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Add
@JsonIgnoreProperties(ignoreUnknown = true)to all capability sub-records that are missing the annotation, ensuring forward compatibility when the MCP spec adds new fields.Problem
The top-level
ClientCapabilitiesandServerCapabilitiesrecords have@JsonIgnoreProperties(ignoreUnknown = true), but their nested sub-records do not. Since theObjectMapperdefaults toFAIL_ON_UNKNOWN_PROPERTIES = true, any unknown field on a capability sub-object causes a deserialization failure.This already caused a real breakage when the elicitation capability gained
formandurlfields (#724, fixed in #731). The systemic issue remains — the next spec addition to any capability sub-object will break older SDK versions.The MCP spec schema explicitly does not close capability objects (
additionalProperties: falseis never set). Several sub-capabilities (sampling,elicitation,completions,logging) explicitly setadditionalProperties: true.Fix
Add
@JsonIgnoreProperties(ignoreUnknown = true)to:ClientCapabilities.SamplingClientCapabilities.ElicitationClientCapabilities.Elicitation.FormClientCapabilities.Elicitation.UrlServerCapabilities.CompletionCapabilitiesServerCapabilities.LoggingCapabilitiesServerCapabilities.PromptCapabilitiesServerCapabilities.ResourceCapabilitiesServerCapabilities.ToolCapabilitiesTesting
Added 9 targeted tests in
McpSchemaTeststhat verify each sub-record correctly ignores unknown fields during deserialization. All existing tests continue to pass.Fixes #766
Related: #734